Failure in standard ignition coils due to a short circuit and recommending reinforced insulation.
| Identifier | ExFiles\Box 164\5\ img070 | |
| Date | 3rd August 1931 | |
| X6058 To Ey. from Hs {Lord Ernest Hives - Chair} /HEW. Hs {Lord Ernest Hives - Chair} /HEW3/ADL 3.8.31. STANDARD IGNITION COILS. We have had a failure on ordinary bench endurance test of a standard D.72503 ignition coil, the fault being due to a short circuit between the top two layers of the secondary winding. This kind of short circuit, presumably owing to its distance from the core, does not have the same choking effect on the main core flux as a bottom layer short circuit so that a definite breakdown does not occur, but only intermittent misfiring. We are now wondering whether some of the D.72503 coils which have been returned as faulty by customers, who complained of misfiring, and pronounced O.K. by the electrical production test dept., were not also suffering from the same trouble. Unless one is cognisant of the symptoms of top layer failure, the misfiring experienced on the test gaps might have been put down to other influencing factors, the coil not being suspected owing to the bottom layer breakdowns having been eliminated. We should like production to carefully watch for any misfiring on the test gaps whenever a D.72503 coil comes back as faulty. This failure is the usual one experienced by all other ignition manufacturers who have had to reinforce the top layer insulation of their coil windings, and we recommend if this type of failure is established on these D.72503 coils that we also put in an extra layer of paper between the top two layers of the secondary winding. Hs {Lord Ernest Hives - Chair} /HEW. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).